Boutin
Jacqueline
Boutin
Jacqueline
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ArticleSatellite and in situ salinity : understanding near-surface stratification and subfootprint variability(American Meteorological Society, 2016-08-31) Boutin, Jacqueline ; Chao, Yi ; Asher, William E. ; Delcroix, Thierry ; Drucker, Robert S. ; Drushka, Kyla ; Kolodziejczyk, Nicolas ; Lee, Tong ; Reul, Nicolas ; Reverdin, Gilles ; Schanze, Julian J. ; Soloviev, Alexander ; Yu, Lisan ; Anderson, Jessica ; Brucker, Ludovic ; Dinnat, Emmanuel ; Santos-Garcia, Andrea ; Jones, W. Linwood ; Maes, Christophe ; Meissner, Thomas ; Tang, Wenqing ; Vinogradova, Nadya ; Ward, BrianRemote sensing of salinity using satellite-mounted microwave radiometers provides new perspectives for studying ocean dynamics and the global hydrological cycle. Calibration and validation of these measurements is challenging because satellite and in situ methods measure salinity differently. Microwave radiometers measure the salinity in the top few centimeters of the ocean, whereas most in situ observations are reported below a depth of a few meters. Additionally, satellites measure salinity as a spatial average over an area of about 100 × 100 km2. In contrast, in situ sensors provide pointwise measurements at the location of the sensor. Thus, the presence of vertical gradients in, and horizontal variability of, sea surface salinity complicates comparison of satellite and in situ measurements. This paper synthesizes present knowledge of the magnitude and the processes that contribute to the formation and evolution of vertical and horizontal variability in near-surface salinity. Rainfall, freshwater plumes, and evaporation can generate vertical gradients of salinity, and in some cases these gradients can be large enough to affect validation of satellite measurements. Similarly, mesoscale to submesoscale processes can lead to horizontal variability that can also affect comparisons of satellite data to in situ data. Comparisons between satellite and in situ salinity measurements must take into account both vertical stratification and horizontal variability.
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ArticleIntraseasonal variability of surface salinity in the eastern tropical pacific associated with mesoscale eddies.(American Geophysical Union, 2019-03-28) Hasson, Audrey ; Farrar, J. Thomas ; Boutin, Jacqueline ; Bingham, Frederick ; Lee, TongStrong variability in sea surface salinity (SSS) in the Eastern Tropical Pacific (ETPac) on intraseasonal to interannual timescales was studied using data from the Soil Moisture and Ocean Salinity, Soil Moisture Active Passive, and Aquarius satellite missions. A zonal wave number‐frequency spectral analysis of SSS reveals a dominant timescale of 50–180 days and spatial scale of 8°–20° of longitude with a distinct seasonal cycle and interannual variability. This intraseasonal SSS signal is detailed in the study of 19 individual ETPac eddies over 2010–2016 identified by their sea level anomalies, propagating westward at a speed of about 17 cm/s. ETPac eddies trap and advect water in their core westward up to 40° of longitude away from the coast. The SSS signatures of these eddies, with an average anomaly of 0.5‐pss magnitude difference from ambient values, enable the study of their dynamics and the mixing of their core waters with the surroundings. Three categories of eddies were identified according to the location where they were first tracked: (1) in the Gulf of Tehuantepec, (2) in the Gulf of Papagayo, and (3) in the open ocean near 100°W–12°N. They all traveled westward near 10°N latitude. Category 3 is of particular interest, as eddies seeded in the Gulf of Tehuantepec grew substantially in the vicinity of the Clipperton Fracture Zone rise and in a region where the mean zonal currents have anticyclonic shear. The evolution of the SSS signature associated with the eddies indicates the importance of mixing to their dissipation.